This invention relates to apparatus for fractioning liquid with centrifugation and for selectively compartmenting or otherwise isolating the fractions.
More particularly, the invention provides a container structure that facilitates separating a liquid, particularly a body fluid, into fractions with centrifugal force, and with high purity of each isolated component and with high yield. The invention also provides improvements for an instrument that centrifugally fractions a liquid and isolates the fractions. The invention is described with reference primarily to the processing of blood. Features of the invention may however be used with other liquids, particularly liquid suspensions containing bone marrow, tissue or other cells.
Human blood has four components which, in order of increasing specific gravity, are: blood plasma, blood platelets, white blood cells and red blood cells. White blood cells and blood platelets, together called buffycoat, constitute in total approximately one percent of the volume of normal blood. Red blood cells account for approximately forty-five percent of the total volume. The blood plasma constitutes the balance, or approximately fifty-four percent. Nominal specific gravities of the blood components are: blood plasma 1.03; red blood cells 1.08 to 1.11; blood platelets 1.05; and white blood cells 1.055 to 1.085.
Blood components can be classified into further constituents which it may be desirable to isolate. For example, white blood cells can further be classified as mononuclear cells and as granulocytes. Red blood cells can be further distinguished between older cells, namely gerocytes, and newly formed cells termed neocytes. The average lifetime of a red blood cell is approximately ninety days. New cells, which are expected to have a relatively longer life, are of greater importance for blood transfusion. The specific gravity of red blood cells increases as they age, so that with the aid of centrifuging it is possible to achieve a distribution of red blood cells according to age.
The demand for different blood components, each with high purity, is significant and is increasing. For example, in order to avoid undesired immunological reactions in patients as a result of transfusion, it often is desirable to administer a patient with only selected blood components.
The extensive publications regarding the fractionation of blood with centrifugal force include European Patent Office patent No. 0,026,417 and PCT international publication No. WO81/03626.
These publications primarily concern mechanisms for subjecting blood to centrifugal force, pumping and other processing to isolate components. There is also significant need, however, for improvements in the container structures that contain the whole blood, from the time of initial collection to fractionating, and the subsequent isolation of the resultant components.
Accordingly, it is an object of this invention to provide container apparatus for liquid being centrifugally fractionated, and the components isolated, and which provides a relatively high degree of constituent purity, with relatively high yield. It is a further object that the container apparatus provide for component separation and isolation in a relatively brief time and be suitable for use with automated processing.
Another object is to provide such container apparatus that maintains closed system sterility after being filled with whole blood.
A further object is that the container apparatus of the above character be suited for low cost manufacture with mass production techniques.
It is also an object of this invention to provide improvements in equipment for centrifugally fractionating liquid, and isolating the fractions, with a relatively high degree of constituent purity and relatively high yield, particularly in brief time and suited for automatic operation.
Other objects of the invention will in part be obvious and will in part appear hereinafter.